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16 Crankcase
Preparing documents -----------------16.1
Failure diagnosis ----------------------16.2
Crankcase ------------------------------16.3
Assembly ------------------------------16.4
16.1 Preparing documents
Work instructions
The crankcase is thin-section casting thus shall not suffer impact during operation which may cause deformation or
fracture.
All components must be cleaned and blown with high-pressure gas before test.
Lubricant in the crankcase should be drained out before operation.
Function of the crankcase
：
The crankcase is the load-bearing part of the engine. Its main function is to
support the crankshaft, clutch, gearbox, cylinder block and cylinder cover, sustain combustion shock and inertia
force from the movement of the connecting rod, and form part of closed space (oil sealing, gas sealing).
Suspension holes in the crankcase are linked with suspension holes in the body, which connects the engine to the
frame and other parts.
Preparing Principles
Unit: mm
Item
Standard
Limit for use
Left-right clearance of the larger end of the
connecting rod
0.1-0.3 0.3
Crankshaft
Radial clearance of the larger end of the
connecting rod
0.008-0.018 0.018
Tools
Universal holder Clutch spring compressor
Screwdriver lever Socket spanner
Guide rod Bearing screwdriver
